A5067485536- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Advancements in Solid Oxide Fuel Cells
- Nuclear Physics and Applications
- Electronic and Structural Properties of Oxides
- Multiferroics and related materials
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- High-pressure geophysics and materials
- Inorganic Fluorides and Related Compounds
- X-ray Diffraction in Crystallography
- Ferroelectric and Piezoelectric Materials
- Thermal Expansion and Ionic Conductivity
- Fuel Cells and Related Materials
- Superconductivity in MgB2 and Alloys
- Transition Metal Oxide Nanomaterials
- Gas Sensing Nanomaterials and Sensors
- ZnO doping and properties
- Magnetic Properties and Synthesis of Ferrites
- Inorganic Chemistry and Materials
- Rare-earth and actinide compounds
- Magnetic Properties of Alloys
- Iron-based superconductors research
- Magnetic Properties and Applications
Oak Ridge National Laboratory
2010-2019
Altoris (United States)
2018
Oak Ridge Associated Universities
2014
Princeton University
2012
Knoxville College
2009
Spallation Neutron Source
2004-2007
Argonne National Laboratory
1997-2002
University of Nottingham
2002
Bariloche Atomic Centre
2000
Balseiro Institute
2000
We characterize experimentally and theoretically the promising new solid oxide fuel cell electrode material Sr(2)Fe(1.5)Mo(0.5)O(6-δ) (SFMO). Rietveld refinement of powder neutron diffraction data has determined that crystal structure this is distorted from ideal cubic simple perovskite, instead belonging to orthorhombic space group Pnma. The revealed presence oxygen vacancies in as-synthesized material, resulting a composition Sr(2)Fe(1.5)Mo(0.5)O(5.90(2)) (δ = 0.10(2)). DFT+U theory...
The defect structure of bulk and nano-indium-tin oxide was investigated by a combination experimental techniques, including high-resolution synchrotron x-ray diffraction, extended absorption fine structure, time-of-flight neutron diffraction on powder specimens. structural results include atomic positions, cation distributions, oxygen interstitial populations for oxidized reduced materials. These parameters were correlated with theoretical calculations in situ electrical conductivity...
The neutron powder diffractometer POWGEN at the Spallation Neutron Source has recently (2017-2018) undergone an upgrade which resulted in increased detector complement along with a full overhaul of structural design instrument. current instrument solid angular coverage 1.2 steradians and maintains original third-generation concept, providing single-histogram data set over wide d-spacing range high resolution to access large unit cells, detailed refinements situ/operando measurements.
The defect structure of undoped and Sn-doped In2O3 (ITO) materials was studied by preparing powders under different processing environments performing neutron powder diffraction. effect tin doping oxygen partial pressure determined. Structural information obtained analyzing diffraction data using the Rietveld method. results include positions atoms, their thermal displacements, fractional occupancy interstitial site, occupancies Sn on each two nonequivalent cation sites. cations show a...
Transition-metal-only double perovskite oxides (A2BB′O6) are of great interest due to their strong and unusual magnetic interactions; only one compound, Mn2FeReO6, was reported in this category date. Herein, we report the second transition-metal-only perovskite, Mn2MnReO6, prepared at high pressure temperature. Mn2MnReO6 crystallizes a monoclinic P21/n structure, as established by synchrotron X-ray powder neutron diffraction (PND) methods, with eight-coordinated A sites rock-salt arrangement...
The layered perovskite NdBaCo2O5+δ (NBCO) was characterized using neutron powder diffraction under in situ conditions from 577–852 °C and 10−1 to 10−4 atm oxygen. best fit the data obtained tetragonal (P4/mmm) space group. No oxygen atom vacancy ordering observed that warranted a lowering of symmetry orthorhombic (Pmmm). Two P4/mmm structural models were investigated: Model 1 (no split sites) 2 (split Nd O2 sites). Transport through material via hopping mechanism likely involves...
Abstract Above‐room‐temperature polar magnets are of interest due to their practical applications in spintronics. Here we present a strategy design high‐temperature magnetic oxides the corundum‐derived A 2 BB′O 6 family, exemplified by non‐centrosymmetric ( R 3) Ni 3 TeO ‐type Mn 2+ Fe 3+ Mo 5+ O , which shows strong ferrimagnetic ordering with T C =337 K and demonstrates structural polarization without any ions n −1)d 10 s 0 d or stereoactive lone‐pair electrons. Density functional theory...
Structures of lithium nitride (α-Li3N) and ternary nitridometalates Li3-x-yMxN (M = Ni, Cu) have been refined from time-of-flight powder neutron diffraction data using the Rietveld method. The parent binary was synthesized by reaction metal with nitrogen liquid sodium as a solvent. nitrides were prepared Li3N respective transition metals under nitrogen. Refined confirm hexagonal structure previously reported single-crystal X-ray for (P6/mmm, 3.6576(1) Å, c 3.8735(1) Z 1) show that α-Li3N...
A two-dimensional (2D) Anger camera detector has been used at the HB-3A four-circle single-crystal neutron diffractometer High Flux Isotope Reactor (HFIR) since 2013. The 2D enabled capabilities of measuring sub-mm crystals and spin density maps, enhanced efficiency data collection phase transition detection, improved signal-to-noise ratio. Recently, undergoing a upgrade towards much larger area, magnetic-field-insensitive, detector. instrument will become capable doing diffraction under...
Transition-metal-only perovskite oxides can introduce additional magnetic functionality with robust magnetoelectric properties but are rare. In this work we prepared a new transition-metal-only Mn2(Fe0.8Mo0.2)MoO6 at high pressure and temperature. Uniquely, was discovered as line phase upon composition modulation that motivated from the above-room-temperature multiferroic Mn2FeMoO6 corundum phase. It exhibits ferrimagnetic Fe–Mo sublattice (TC = 194 K) Mn antiferromagnetic (Tm ∼ 45...
We have expanded the double perovskite family of materials with unusual combination layered order in A sublattice and rock salt over B to compounds NaLaFeWO6 NaNdFeWO6. The been synthesized studied by powder X-ray diffraction, neutron electron magnetic measurements, absorption spectroscopy, dielectric second harmonic generation. At room temperature, crystal structures both can be defined noncentrosymmetric monoclinic P21 space group resulting from ordering sublattices, distortion cell due...
Pb2MnTeO6, a new double perovskite, was synthesized. Its crystal structure determined by synchrotron X-ray and powder neutron diffraction. Pb2MnTeO6 is monoclinic (I2/m) at room temperature with regular arrangement of all the cations in their polyhedra. However, when lowered to ∼120 K it undergoes phase transition from I2/m C2/c structure. This accompanied displacement Pb atoms center polyhedra due 6s2 lone-pair electrons, together surprising off-centering Mn2+ (d5) magnetic cations. strong...
The magnetism of Sr$_2$F$_2$Fe$_2$OS$_2$ was examined through neutron powder diffraction and thermodynamic transport measurements. Quasi-two-dimensional magnetic order develops below $T_N$ = 106(2) K with an in-plane correlation length exceeding 310 \AA\ out-of-plane just 17(3) \AA. data are consistent a two-k structure $k_1$ (1/2, 0, 1/2) $k_2$ (0, 1/2, ordered moment 3.3(1) $\mu_B$ oriented along the components k. This is composed orthogonal AFM chains intersecting at super-exchange...
This paper describes the design criteria, calculations and simulations for a high-resolution macromolecular neutron diffractometer (MaNDi) Spallation Neutron Source (SNS). MaNDi is optimized to achieve 1.5 Å resolution from crystals of 0.1–1 mm 3 with lattice repeats in range 150 Å. It was determined that locating on decoupled hydrogen moderator beamline curved guide will provide data higher signal-to-noise than coupled at SNS. In addition, an instrument initial flight path 24 m 60 Hz source...